Injuries to Gibbins and Matt Smith ave given Fusaro the opportunity for a run of games, and his fine form since has been acknowledged by Rennie's making him captain for some games.
Speaking in The Scotsman, Fusaro said: "It has been a good run. Obviously, there were a couple of injuries in my position, so one man's misfortune is another man's good fortune. I've had a decent run of games, which gives you a bit of confidence.
"As I get older, there are more and more young guys coming through - the likes of Matt Smith, Bruce Flockhart and people like that - so to keep getting opportunities is very important. You want to keep showing what you can do."
Fusaro's starts were limited last season but he's grabbed his opportunities this term and impressed enough to be rewarded with a new two-year contract.
"I don't think I've changed, really," he continued when asked if any alteration in attitude had helped persuade the coaching team to select him more consistently. "Dave came in and didn't really know me, but he has got to know me over the last couple of years. I don't want to sound arrogant, but he seems to like what he sees and that's good for me."